Constant-current arc-welding system



W. B. ELLIOTT AND W. OBLENIS.

CONSTANT CURRENT ARC WELDING SYSTEM.

APPLICATION FILED MAR. 14, 1918.

1,412,463; Patented Apr. 11, 1922.

. INVENTORS BY fit ALv-fi ATTORNEY UNITED STATES PATENT-OFFICE.

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Specification 0t Letters2aten t.: Pate t d A 11 1 2 I .Application filedMarch 14, 1918. Serial No. 222,277.

Toall whom it may concern:

Be it known that we, WILLIAM B. ELLIo'rr and WILLIAM [-OBLnms, citizensof the United States, both residing at Westfield,

county of Union, State of New Jersey, have invented new and usefulImprovementsin Constant-Current Arc-Welding Systems,- of which thefollowing is a speclfication.

This invention relates to a system for welding, brazing or otherwisetreating metals by means of the electric arc,

Where the arc is fed from a constant potential, it is very unstable.This has been overcome to some extent by placing resistance in circuitwith the are, but this is a wasteful proceeding. A much more efficientmethod is to vary the voltage impressed on the arc electrode accordingto the resistance of the arc. For this purpose, the generator .supplyinthe voltage may be so regulated that the field excitation, andconsequently the voltage will be lowered when the current increases, dueto --the lowering of the resistance of the arccircuit as by decrease inthe resistance of the arc. Conversel the excitation of the generatorshoul be increased with anincrease in the resistance of the arc circuit.4

The present invention has for its main object the provision of improvedmeans for effecting the regulation of the voltage in the arc circuit,which means is especially adapted to regulate the voltage in the man- Iner as just described and which is also suitable for regulationof thearc circuit in other respects.

Other and ancillary objects of the invention will appear hereinafter.

The accompanying drawing, which illustrates the invention, isadiagrammatic I showing of apparatus and connections of a" systemembodying the invention.

Referring to the drawing, the arc is adapted to be formedbetween thework 1 andan electrode 2, and is supplied with current by means of adirect current gen- .erator including the armature 3, the series field 4and the field 5, One terminal of the armature 3 is connected through theseries field 4: and the series field 6 of an exciter to be furtherreferred to hereinafter, with the electrode 2. The other terminal of thegenerator is connected with the work 1. The field 5 is supplied withcurrent by a compound wound exciter comprising the armature otherterminal of the field 5. The rheostat 10 is forthepurpose of initialadjustment of the field current in winding 5. The main generator has itsfields arranged differentially, that is, the fields 4 and 5 are opposedThe series field may to each other so that as the series fieldstrengthens, the total field excitation of generator will be reduced.-The exciter being compound wound, the shunt and series-fields 8 and 6act in conjunction so that a strengthening of the series fieldstrengthens the resultant field on the exciter; V

Withthe electrodes 1 and 2 separated and no current flowing, the voltageof the'main generator supplying the arc will be that due to its field 5,which is excited by the exclter armature 7 subjected to the excitationof the shunt field 8 only. The series fields 4 and 6 have no effect asno current is flowing. Under these conditions, the voltage is such thatwhen the electrodes 1 and 2 are touched together to strike the are therewill not be an undue' rush of current. As soon as current flows in thearc circuit, however, the current through the series field 6 of theexciter, will cause an increase in the field of the exciter with aconsequent 'increase'in the voltage, with a resultant increase incurrent through the field 5, which tends to increase the strength of thefield of the main generator and therefore its voltage. The voltagetherefore impressed on' the arc circuit is increased over the lowvoltage which exists at the timethe electrodes are brought together, buta great rush of current is prevented by reason of the fact that thebucking series field a which carries the working current, decreases thethe main generator voltage. Normal workto. decrease in the arc circuitresistance and conversely it will tend to prevent decrease of current inthe arc circuit upon an %Vhat we claiinis- 1.' The combination of acircuit having a load device varying widely in resistance, a generatorsupplying said load device, said generator comprising a main fieldw1nding,

. an auxiliary source of electromotive force supplying said main fieldwinding, and means responsive to conditions in said circuit forregulating said source, said generator also comprislng a seriesfieldwinding opposed to said main field winding.

2. The combination of a circuit having a generator supplying saidload-device, said generator comprising a main field winding,

and an auxilia generator su plying said main field win ing, said auxiiary generator having a shunt field winding and a field windin connectedin series in said circuit, said rst named generator also having a seriesfield winding opposed to said main field winding.

The combination of a circuit having a load device varying widely inresistance, a generator supplying said load device, said generatorcomprising a main field winding, and an auxiliary generator supplyingsaid main field windin said auxiliary genera-tor having a shunt eldwinding and a field winding connected in series in said circuit and saidlast two named windings having an additive effect, said first namedgenerator having a series field winding opposed to said main fieldwindin In testimony wIxereof we have signed this specification this 23dday of February,

' WILLIAM B. ELLIOTT.

WILLIAM OBLENIS.

